3-Exomethylenecepham compounds were first described by Morin and Jackson in U.S. Pat. No. 3,275,626 wherein their formation in the penicillin sulfoxide rearrangement is discussed. R. R. Chauvette describes in U.S. Pat. No. 3,932,393 a process for the preparation of 3-exomethylenecepham compounds from 3-thio-substituted-methylcephalosporin compounds under chemical and catalytic reduction conditions. M. Ochiai, et al. describe in U.S. Pat. No. 3,792,995 an electrolytic reduction process for the preparation of 3-exomethylenecepham compounds, and in U.S. Pat. No. 3,929,775, a reduction process employing chromous salts, both of which processes can be carried out on cephalosporanic acids. Further, Ponticello et al. describe in U.S. Pat. No. 3,883,518 the reduction of 3-acetoxymethyl and 3-carbamoyloxymethyl substituted 7-methoxycephalosporin compounds with, for example, zinc dust and formic acid to prepare 7-methoxy-3-exomethylenecepham compounds.
Chauvette in U.S. Pat. No. 3,932,393 further teaches a process for the isomerization of the 3-exomethylenecepham compounds to 3-methyl-3-cephem compounds, desacetoxycephalosporanic acids, which are well known antibiotic compounds.
Co-pending application Ser. No. 278,668, now abandoned, describes a process for electrolytically reducing 3-thio-substituted methylcephalosporins and cephalosporanic acids to 3-exomethylenecepham compounds.
This invention is concerned with a reduction process for the preparation of 7-methoxy-3-exomethylenecepham compounds. In particular this invention is concerned with a process for the electrolytic reduction of 7-methoxy substituted cephalosporanic acids and 7-methoxy-3-substituted-methylcephalosporin compounds to provide 7-methoxy-3-exomethylenecepham compounds.